Traditionally, antenna elements have been designed using perfect electrical conductors often placed above a perfect electrically conducting ground-plane. A dipole element is typically utilized and spaced one quarter wavelength above the ground-plane. A perfect electrical conductor has the property that when an electromagnetic wave impinges on the surface it is reflected with a 180 degree change in phase. Thus if the dipole element is one quarter wavelength corresponding to a 90 degree phase shift then the reflected component has a 360 degree total phase change and is hence in phase with the radiating signal reinforcing radiation away from the ground-plane reflector. Small variations of the one quarter wavelength spacing are used to adjust the effective radiating beam-width. This requirement for one quarter wavelength separation between the ground-plane and the radiating element limits the thickness of the antenna.
There is often a need to design low profile antennas. In some cases this can be met by using alternative elements such as patches. These elements do not always provide the necessary radiation patterns or other required characteristics. Therefore, alternative designs are desired.